There are more issues than this, reserves would be another. 

Lenders will require the borrower to have the 15-20% down payment plus any reserve requirements for underwriting purposes.Regarding your question: Are you asking if you need to have the 20% difference in cash to bring to the first mortgage closing and then have the seller lend it back to you right after closing?

Some programs may allow for up to 85% financing assuming great credit and meeting reserve requirements. 

Second by the purchasing party having financial reserves or borrowing capacity to handle acceleration of the note.3.

Take into consideration the mortgage, taxes, insurance, HOA fees, and cash reserves for home repairs or replacements.

It may be time-consuming, but if you do your research and confirm there are no challenges, you can proceed confidently.

A good idea is to accrue a capital investment reserve from operating cashflows, for such events.

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23If a purchase, you also generally need reserves / savings to show you have 3-6 month payments of PITIA (principal / interest (mortgage payment), property taxes and insurance and HOA (if applicable).

But just consider a $1250/month rental that after all expenses (including the loan, maintenance, Capex reserve, taxes, insurance, etc) nets you $300/month clear.Now scale that just a little and say you have 8 units, just to run with your scenario above.  

We are 4 younger guys recently out of college looking at forming an LLC to purchase our first investment property. We planning to meet with a lawyer soon to cement our articles of organizations and operating agreement...